Heat exchanger with inserts having a stress absorber

ABSTRACT

A heat exchanger comprising: a core portion including a plurality of tubes; a pair of header tanks communicating with the tubes; and a pair of inserts arranged substantially parallel to the length of the tubes, and in such a manner as to contact the core portion at the ends of the core portion to transfer the heat from the core portion, and having the ends thereof supported on the header tanks; wherein a stress absorber to absorb the stress generated along the length of each insert is formed in the insert; wherein the stress absorber is formed over each insert from the upstream side to the downstream side in the air flow; and wherein the stress absorber is arranged in such a manner that the most upstream end and the most downstream end thereof in the air flow are not superposed, one on the other, along the direction of air flow.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional application of Ser. No. 11/974,891,filed Oct. 16, 2007 which is a continuation-in-part application of Ser.No. 11/484,519 filed on Jul. 11, 2006, claiming priority of JapanesePatent Application Nos. 2006-281454 filed Oct. 16, 2006, 2006-157725filed Jun. 6, 2006 and 2005-202807 filed Jul. 12, 2005.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a heat exchanger or, in particular, to a heatexchanger effectively applicable to a multiflow radiator for cooling thecooling water of the internal combustion engine of an automotivevehicle.

2. Description of the Related Art

The conventional multiflow radiator includes a core portion having aplurality of tubes, a header tank communicating with the plurality ofthe tubes and an insert arranged at the end of the core portion forreinforcing the core portion. Also, the header tank is configured of acore plate coupled with the tubes and a tank body providing an internalspace of the tank. The tubes and the insert are inserted in the headtank and coupled to the core plate. Under these conditions, the tubesare held by equal forces by the insert through the fins.

In this radiator, the temperature of the cooling water flowing in thetubes may undergo a change. The amount of thermal expansion is differentbetween the tubes directly affected by the cooling water and the insertaffected indirectly by the cooling water. The difference in the amountof thermal expansion between the tubes and the insert is liable togenerate thermal stress due to thermal distortion at the root (coupling)between the core plate and the tubes adjacent to the insert. A repeatedchange in temperature and hence a repeated change in thermal stressposes the problem that the tubes in the neighborhood of the root may bebroken.

To obviate this problem, an anti-thermal distortion structure has beenproposed in which the thermal distortion is absorbed by cutting thelongitudinal central portion of the insert (Japanese Unexamined PatentPublication No. 11-325783).

In another conventional anti-thermal distortion structure that has beenproposed, an expansion having a substantially semicircular cross sectionis formed on the insert and adapted to be deformed to absorb the thermaldistortion (Japanese Unexamined Patent Publication No. 11-237197).

In the anti-thermal distortion structure proposed in Japanese UnexaminedPatent Publication No. 11-325783, however, the notch of the insertreduces the strength to hold the tubes. In the case where the internalpressure in the tubes increases and the tubes expand under the pressureof the cooling water, the notch of the insert is locally deformed due tothe pressure in the tubes. As a result, the portion of the tube adjacentto the notch is deformed by expansion and may break.

The anti-thermal distortion structure proposed by Japanese UnexaminedPatent Publication No. 11-237197 also poses a similar problem toJapanese Unexamined Patent Publication No. 11-325783 due to the factthat the tube holding strength of the expansion of the insert isreduced.

SUMMARY OF THE INVENTION

In view of this fact, the object of the present invention is to providea heat exchanger in which the thermal distortion is reduced while, atthe same time, the pressure resistance performance is secured.

In order to achieve the object described above, according to a firstaspect of the invention, there is provided a heat exchanger comprising acore portion (4) including a plurality of tubes (2) with a heat mediumflowing therein, a pair of header tanks (5) extending in a directionperpendicular to the length of the tubes (2) at the longitudinal ends ofthe tubes (2) and communicating with the tubes (2), and a pair ofinserts (6) arranged substantially parallel to the length of the tubes(2) in such a manner as to contact the core portion (4) at the ends ofthe core portion (4) and each having the ends thereof supported on thecorresponding header tank (5), wherein, in order to absorb the stressgenerated along the length of each insert (6), a stress absorber (74,76, 77) is formed over the distance from the upstream side to thedownstream side of the insert (6) in the air flow in such a manner thatthe most upstream end and the most downstream end of the stress absorber(74, 76, 77) in the air flow are not superposed, one on the other, alongthe direction of air flow.

By forming the stress absorber (74, 76, 77) in the insert (7) asdescribed above, the stress generated along the length of the insert (7)can be absorbed. Also, in view of the fact that the stress absorber (74,76, 77) is formed with the most upstream and the most downstream endsthereof in the air flow not superposed one on the other along thedirection of air flow, the stress absorber (74, 76, 77), i.e. theportion of the insert (7) having a weak force to hold the tubes (2) canbe dispersed over the length of the tubes (2). In the case where theinternal pressure of the tubes (2) increases, therefore, the insert (7)is prevented from being deformed locally by the stress absorber (74, 76,77). In this way, the tubes (2) are prevented from being broken byexpansion and deformation. As a result, the thermal distortion can bereduced while at the same time the pressure resistance performance issecured.

Each tube (2) may have a flat cross section in the direction of airflow, and the insert (7) may include a base portion (71) having asurface substantially parallel to the flat surface (2 a) of the tube (2)and extending substantially in parallel to the length of the tube (2),and ribs (72) projected in a direction substantially perpendicular tothe base portion (71) from the ends of the base portion (71) in thedirection of air flow and are extended substantially parallel to thelength of the tube (2), wherein the portions of the ribs (72)corresponding to the most upstream and the most downstream ends of thestress absorber are formed with notches (73 a, 73 b), respectively, andthe stress absorber constitutes a base portion-side expansion (74)having a substantially U-shaped cross section of the base portion (71).

A “substantial U shape” is a shape configured of two substantiallyopposed parallel surfaces and a substantially arcuate bottom surfaceconnected to the two surfaces, in which the bottom surface may include ahorizontal portion. In other words, the cross section may besubstantially channel-shaped.

In this case, the base portion-side expansion (74) may be tilted withrespect to the direction of air flow.

According to a second aspect of the invention, there is provided a heatexchanger wherein the base portion-side expansion (74) is split into aplurality of portions in the direction of air flow, which are connectedto each other through slits (75) formed in the cross section of the baseportion (71).

As a result, the length of the base portion-side expansion (74) alongthe direction of air flow can be reduced by the length of the slits (75)in the direction of air flow, thereby improving the moldability.

According to a third aspect of the invention, there is provided a heatexchanger wherein a plurality of the base portion-side expansions (74)are not aligned.

As a result, the distance between the notch (73 a) on the upstream sidein the air flow and the notch (73 b) on the downstream side in the airflow can be increased without increasing the angle that the baseportion-side expansion (74) forms with the direction of air flow. Thus,the pressure resistance performance can be positively secured withoutdeteriorating the moldability of the base portion-side expansion (74).

According to a fourth aspect of the invention, there is provided a heatexchanger wherein the plurality of the base portion-side expansions (74)are tilted in different directions from the direction of air flow.

This configuration can reduce the spring back at the time of molding theplurality of the base portion-side expansions (74) and thus improve themoldability.

According to a fifth aspect of the invention, there is provided a heatexchanger wherein the plurality of the base portion-side expansions (74)are arranged substantially parallel to the direction of air flow in sucha manner as not be superposed one on another in the direction of airflow.

This configuration eliminates the need of tilting the base portion-sideexpansions (74) from the direction of air flow and therefore themoldability can be improved.

According to a sixth aspect of the invention, there is provided a heatexchanger wherein each tube (2) has a flat cross section in thedirection of air flow and the insert (7) includes a base portion (71)having a surface substantially parallel to the flat surface (2 a) of thetube (2) and extending in the direction substantially parallel to thelength of the tube (2) and ribs (72) projected in the directionsubstantially perpendicular to the base portion (71) and extending inthe direction substantially parallel to the length of the tube (2), andwherein the stress absorber is a notch (76), cut in the base portion(71), diagonal to the direction of air flow.

As a result, the stress absorber can be configured of only the notch(76) formed in the insert (7), and therefore the pressure resistanceperformance can be secured with a simple configuration.

According to a seventh aspect of the invention, there is provided a heatexchanger wherein only one end of the notch (76) is open.

This configuration leaves one of the ribs (72) intact and can avoidreducing a rigidity more than requires. As a result, the force to holdthe tubes (2) can be increased. Thus, the thermal distortion can bereduced while, at the same time, positively securing the pressureresistance performance.

Alternatively, the two ends of the notch (76) may be open or connectedto each other.

Further, a plurality of the notches (76) may be formed.

Furthermore, only one end of each of a plurality of notches (76) may beopen, and the open ends of the plurality of the notches (76) may bearranged alternately between the upstream side and the downstream sideof the base portion (71) in the air flow.

In addition, the plurality of the notches (76) can be tilted indirections different from the direction of air flow.

According to an eighth aspect of the invention, there is provided a heatexchanger wherein the notch (76) is formed in the base portion (71), theportion of the pair of the ribs (72) adjoining the notch (76) is formedwith a U-shaped rib-side expansion (77) in the direction of air flow,and the stress absorber includes the rib-side expansion (77).

By forming at least a notch (76) in the base portion (71) and therib-side expansions (77) on a pair of the ribs (72) in this way, thestress generated along the length of each insert can be positivelyabsorbed.

According to a ninth aspect of the invention, the insert (7) is formedwith protrusions (78) projected outward along the direction in which thetubes (2) are stacked and connected to a stress absorber (74, 76, 77).

Upon application of a pressure (when the internal pressure of the tubes(2) increases), the whole heat exchanger (1) is deformed to expand alongthe direction in which the tubes (2) are stacked, and upon vibration,the whole heat exchanger (1) is deformed along both the length of thetubes (2) and the direction in which the tubes (2) are stacked. Theprovision of the protrusions (78) of the insert (7) projected outwardalong the direction in which the tubes (2) are stacked, however, makesit possible to increase the stiffness of the insert (7) along thedirection in which the tubes (2) are stacked. As a result, the pressureresistance and the earthquake resistance are improved.

According to a tenth aspect of the invention, the tubes (2) have a flatsection along the direction of air flow, the insert (7) includes a baseportion (71) having a surface substantially parallel to the flat surfaceof the tubes (2) and extending in the direction substantially parallelto the length of the tubes (2), the base portion (71) has baseportion-side ribs (78) projected outward along the direction in whichthe tubes (2) are stacked and extending in the direction substantiallyparallel to the length of the insert (7), the stress absorbing portionis a base portion-side expansion (74) of the base portion (71) havingthe section expanded substantially in the shape of U, and an end of eachof the base portion-side ribs (78) is connected to the base portion-sideexpansion (74).

As described above, in view of the fact that the base portion (71) ofthe insert (7) is formed with the base portion-side ribs (78) projectedoutward along the direction in which the tubes (2) are stacked, thestiffness of the insert (7) in the direction along which the tubes (2)are stacked can be improved, thereby improving the pressure resistanceand the earthquake resistance.

The stress, if generated along the length of the insert (7), may beconcentrated at the connector between the base portion (71) of theinsert (7) and the base portion-side expansion (74) and may damage theconnector. By connecting an end of each of the base portion-side ribs(78) to the base portion-side expansion (74), however, the stress isprevented from being concentrated on the connector between the baseportion (71) and the base portion-side expansion (74).

According to an eleventh aspect of the invention, the insert (7) has apair of side ribs (72) projected in the direction substantiallyperpendicular to the base portion (71) from the ends of the base portion(71) along the direction of air flow, and the parts of the side ribs(72) corresponding to the most upstream end and the most downstream endof the base portion-side expansion (74) are formed with notches (73 a,73 b).

In view of the fact that the base portion (71) of the insert (7) isformed with the base portion-side ribs (78) projected outward along thedirection in which the tubes (2) are stacked as described above, thestiffness of the insert (7) along the direction in which the tubes (2)are stacked can be improved. As a result, even in the case where theheight (length along the direction in which the tubes (2) are stacked)of the side ribs (72) is reduced, the stiffness of the insert (7), i.e.the strength of the heat exchanger (1) can be secured. Even in the casewhere the mounting space of the heat exchanger (1) is limited,therefore, the height (length along the direction in which the tubes (2)are stacked) of the core portion (4) can be increased by the amountcorresponding to the height reduction of the side ribs (72), andtherefore, the heat exchange performance is improved.

According to a twelfth aspect of the invention, the base portion-sideribs (78) are arranged in a pair on both sides, respectively, of thebase portion-side expansion (74).

As a result, the base portion-side ribs (78) can be arranged over a widerange along the length of the insert (7). Thus, the stiffness of theinsert (7) along the direction in which the tubes (2) are stacked can befurther increased for a further increased pressure resistance andearthquake resistance.

In the twelfth aspect described above, the base portion-side ribs (78)can be arranged on one and the other sides, respectively, of the centerline (L) of the base portion (71) along the direction of air flow acrossthe length of the insert (7). As a result, the base portion-side ribs(78) can be arranged over a wide range of the insert (7) in thedirection of the air flow, and therefore, the stiffness of the insert(7) along the direction in which the tubes (2) are stacked can befurther increased. Thus, the pressure resistance and the earthquakeresistance are further improved.

According to a thirteenth aspect of the invention, the base portion (71)is formed with second base portion-side ribs (78 a) projected outwardalong the direction in which the tubes (2) are stacked and extendingsubstantially in parallel to the length of the insert (7). This makes itpossible to increase the stiffness of the insert (7) along the directionin which the tubes (2) are stacked for an improved pressure resistanceand an improved earthquake resistance.

According to a fourteenth aspect of the invention, the base portion-sideribs (78) are arranged on one and the other sides, respectively, of thecenter line (L) of the base portion (71) along the direction of air flowacross the length of the insert (7), the base portion (71) has secondbase portion-side ribs (78 a) projected outward along the direction inwhich the tubes (2) are stacked and extending substantially in parallelto the length of the insert (7), the second base portion-side ribs (78a) are each arranged on one of the two sides of the base portion-sideexpansion (74), i.e. on one and the other sides, respectively, of thecenter line (L) of the base portion (71) along the direction of air flowacross the length of the insert (7), and the second base portion-sideribs (78 a) are arranged in opposed relation to the base portion-sideribs (78) with respect to the base portion-side expansion (74) on oneand the other sides, respectively, of the center line (L).

As a result, the stiffness of the insert (7) along the direction inwhich the tubes (2) are stacked can be further increased for an improvedresistance to pressure and earthquake.

In the fourteenth aspect described above, an end of each of the secondbase portion-side ribs (78 a) can be connected to the base portion-sideexpansion (74). As a result, the stress concentration on the connectorbetween the base portion (71) and the base portion-side expansion (74)can be more positively prevented.

Also, the base portion-side ribs (78) are each arranged, on one of thesides of the base portion-side expansion (74) and aligned with eachother, the base portion (71) is formed with second base portion-sideribs (78 a) projected along the direction in which the tubes (2) arestacked and extending substantially in parallel to the length of theinsert (7), and the second base portion-side ribs (78) are each arrangedon one of the two sides of the base portion-side expansion (74) andconnected to the base portion-side ribs (78), respectively.

According to a fifteenth aspect of the invention, a notch (76) isextended to the side ribs (72), the ends of the notch (76) are arrangedin the planes of a pair of the side ribs (72), the insert (7) is formedwith second notches (79) substantially parallel to the notch (76) fromthe outer end of the side ribs (72) along the direction in which thetubes (2) are stacked, and only one end of each of the second notches(79) is open.

As a result, the side ribs (72) of the insert (7) are not fully cut, andtherefore, the stiffness of the insert (7) is prevented from beingunnecessarily decreased, thereby making it possible to positivelyincrease both the pressure resistance and the quake resistance.

Further, the notch (76) and the second notches (79) are formed beforepress forming the insert (7), and therefore, the formability isimproved.

In the present specification, the expression “substantially parallel” or“substantially in parallel” should be interpreted not necessarily tomean “completely parallel” or “completely in parallel” but may beinterpreted to mean “almost parallel” or “almost in parallel”.

Incidentally, the reference numerals in parentheses, to denote the abovemeans, are intended to show the relationships between the specific meanswhich will be described later in an embodiment of the invention.

The present invention may be more fully understood from the descriptionof preferred embodiments of the invention, as set forth below, togetherwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of the radiator 1 according to a firstembodiment.

FIG. 2A is a plan view showing the insert 7 according to the firstembodiment.

FIG. 2B is a front view of FIG. 2A.

FIG. 3A is a plan view showing the insert 7 according to a secondembodiment.

FIG. 3B is a front view of FIG. 3A.

FIG. 4A is a plan view showing the insert 7 according to a thirdembodiment.

FIG. 4B is a front view of FIG. 4A.

FIG. 5A is a plan view showing the insert 7 according to a fourthembodiment.

FIG. 5B is a front view of FIG. 5A.

FIG. 6A is a plan view showing the insert 7 according to a fifthembodiment.

FIG. 6B is a front view of FIG. 6A.

FIG. 7A is a plan view showing the insert 7 according to a sixthembodiment.

FIG. 7B is a front view of FIG. 7A.

FIG. 8A is a plan view showing the insert 7 according to a seventhembodiment.

FIG. 8B is a front view of FIG. 8A.

FIG. 9A is a plan view showing the insert 7 according to an eighthembodiment.

FIG. 9B is a front view of FIG. 9A.

FIG. 10A is a plan view showing the insert 7 according to a ninthembodiment.

FIG. 10B is a front view of FIG. 10A.

FIG. 11A is a plan view showing the insert 7 according to a tenthembodiment.

FIG. 11B is a front view of FIG. 11A.

FIG. 12 is a perspective view showing the insert 7 according to thetenth embodiment.

FIG. 13 is a perspective view showing the insert 7 according to aneleventh embodiment.

FIG. 14A is a view taken along arrow A in FIG. 13.

FIG. 14B is a sectional view taken along line B-B in FIG. 13.

FIG. 14C is a sectional view taken along line C-C in FIG. 13.

FIG. 15 is a perspective view showing the insert 7 according to atwelfth embodiment.

FIG. 16A is a view taken along arrow D in FIG. 15.

FIG. 16B is a sectional view taken along line E-E in FIG. 15.

FIG. 16C is a sectional view taken along line F-F in FIG. 15.

FIG. 17 is a perspective view showing the insert 7 according to athirteenth embodiment.

FIG. 18 is a perspective view showing the insert 7 according to afourteenth embodiment.

FIG. 19 is a perspective view showing the insert 7 according to afifteenth embodiment.

FIG. 20 is a perspective view showing the insert 7 according to asixteenth embodiment.

FIG. 21 is a perspective view showing the insert 7 according to aseventeenth embodiment.

FIG. 22 is a perspective view showing the insert 7 according to aneighteenth embodiment.

FIG. 23 is a perspective view showing the insert 7 according to anineteenth embodiment.

FIG. 24 is a plan view schematically showing the insert 7 before bendingthe side ribs 72 according to the nineteenth embodiment.

FIG. 25 is a perspective view showing the insert 7 according to atwentieth embodiment.

FIG. 26 is a perspective view showing the insert 7 according to atwenty-first embodiment.

FIG. 27 is a perspective view showing the insert 7 according to atwenty-second embodiment.

DESCRIPTION OF PREFERRED EMBODIMENTS

The first embodiment of the invention is explained below with referenceto FIGS. 1, 2. This embodiment is an application of the heat exchangeraccording to this invention to the radiator 1 for exchanging heatbetween the air and the cooling water (heat medium) that has cooled thevehicle engine. FIG. 1 is a front view of the radiator 1 according tothe first embodiment.

In FIG. 1, the cooling water flows in the tubes 2. Each tube 2 is flatso that the direction of air flow (direction perpendicular to the page)coincides with the direction of the long diameter, and a plurality ofthe tubes 2 are arranged in parallel to each other in vertical directionin such a manner that the longitudinal direction thereof coincides withthe horizontal direction.

The flat surfaces on the two sides of each tube 2 are coupled with thecorrugated fins 3, whereby the heat transfer area with the air isincreased to promote the heat exchange between the cooling water and theair. The substantially rectangular heat exchange unit including thetubes 2 and the fins 3 is hereinafter referred to as the core portion 4.

The header tank 5 extends in the direction (vertical direction in thisembodiment) perpendicular to the length of the tubes 2 at eachlongitudinal end (horizontal ends in this embodiment) of the tubes 2 andcommunicates with a plurality of the tubes 2. The header tank 5 includesa core plate 5 a coupled with the tubes 2 inserted therein and a tankbody 5 b providing the internal space of the tank with the core plate 5a.

The header tank 5 includes a cooling water inlet 6 a connected to thecooling water outlet side of the engine (not shown) and a cooling wateroutlet 6 b connected to the cooling water inlet side of the engine.Also, an insert 7 for reinforcing the core portion 4 extends in thedirection substantially parallel to the length of the tubes 2 at eachend of the core portion 4.

FIG. 2A is a plan view showing the insert 7 according to the firstembodiment, and FIG. 2B a front view of FIG. 2A. As shown in FIGS. 2A,2B, the insert 7 includes a base portion 71 having a surfacesubstantially parallel to the flat surface 2 a of the tubes 2 andextending in the direction substantially in parallel to the length ofthe tubes 2 and a pair of ribs 72 projected from the ends of the baseportion 71 along the air flow in the direction (direction of tube stack)substantially perpendicular to the base portion 71 and extending in adirection substantially parallel to the length of the tubes 2.

The pair of the ribs 72 of the insert 7 are formed with notches 73 a, 73b, respectively, cut inward in the direction of the tube stack from theouter end of the ribs 72 in the direction of the tube stack. Also, thenotch (hereinafter referred to the upstream side notch 73 a) formed inthe rib 72 on the upstream side in the air flow and the notch(hereinafter referred to as the downstream side notch 73 b) formed inthe rib 72 on the downstream side in the air flow are arranged in such amanner as not be superposed, one on the other, in the direction of airflow.

The base portion 71 of the insert 7 is formed with a base portion-sideexpansion 74. The base portion-side expansion 74 is formed by expandingthe cross section of the base portion 71 substantially into a U shape inthe direction of the tube stack. Also, the base portion-side expansion74 is so configured to be deformed to absorb the tension or compressionstress generated along the length of the insert 7.

As shown in FIG. 2A, the base portion-side expansion 74 is formed toconnect the upstream-side notch 73 a and the downstream-side notch 73 band is arranged diagonally to the direction of air flow.

As explained above, the base portion 71 of the inset 6 is formed withthe base portion-side expansion 74 having a substantially U-shaped crosssection, and therefore the stress generated along the length of theinsert can be absorbed.

Also, by arranging the base portion-side expansion 74 diagonally to thedirection of air flow, the stress absorber of the insert 7, i.e. theportion of the insert 7 weak in the force to hold the tube 2 can bedispersed over the length of the tube. As a result, in the case wherethe internal pressure of the tube 2 increases, the base portion-sideexpansion 74 of the insert 7 can be prevented from being locallydeformed. Thus, the tube 2 is prevented from being deformed by expansionthereby preventing the breakage of the tube 2.

Thus, the thermal distortion is reduced and the pressure resistanceperformance is secured at the same time.

Next, a second embodiment of the invention will be explained withreference to FIGS. 3A, 3B. In FIGS. 3A, 3B, component parts similar oridentical to those of the first embodiment are designated by the samereference numerals, respectively, and are not described again. FIG. 3Ais a plan view showing the insert 7 according to the second embodiment,and FIG. 3B a front view of FIG. 3A.

As shown in FIGS. 3A, 3B, the base portion 71 of the insert 7 accordingto this embodiment is formed with a slit 75. According to thisembodiment, the slit 75 is arranged with the length thereofsubstantially parallel to the length of the tubes 2.

Also, the base portion-side expansion 74 is split into two parts in thedirection of air flow. Of the two base portion-side expansions 74 thussplit, the one arranged upstream in the air flow is called a first baseportion-side expansion 74 a and the one arranged downstream in the airflow a second base portion-side expansion 74 b.

The two base portion-side expansions 74 a, 74 b are connected to eachother through the slit 75. Also, the two base portion-side expansions 74a, 74 b are arranged out of alignment. According to this embodiment, thetwo base portion-side expansions 74 a, 74 b are connected to thelongitudinal ends, respectively, of the slit 75.

As a result, effects similar to those of the first embodiment areproduced.

Further, in view of the fact that the base portion-side expansion 74 issplit into two parts in the direction of air flow and the two baseportion-side expansions 74 a, 74 b thus split are connected to eachother through the slit 75, the length of the base portion-side expansion74 can be reduced by the length of the slit 75 in the direction of airflow. As a result, the moldability is improved.

Also, in view of the fact that the two base portion-side expansions 74a, 74 b are not arranged in alignment, the distance between theupstream-side notch 73 a and the downstream-side notch 73 b in the airflow can be increased without changing the angle of the baseportion-side expansion 74 with respect to the direction of air flow. Asa result, the pressure resistance performance can be positively securedwithout reducing the moldability of the base portion-side expansion 74.

Next, a third embodiment of the invention will be explained withreference to FIGS. 4A, 4B. In FIGS. 4A, 4B, component parts similar oridentical to those of the second embodiment are designated by the samereference numerals, respectively, and not described again. FIG. 4A is aplan view showing the insert 7 according to the tenth embodiment, andFIG. 4B a front view of FIG. 4A.

As shown in FIG. 4A, the two base portion-side expansions 74 a, 74 baccording to this embodiment are tilted in opposite directions withrespect to the direction of air flow.

More specifically, the end of the slit 75 connected with the first baseportion-side expansion 74 a is arranged nearer to the downstream-sidenotch 73 b than to the upstream-side notch 73 a in the direction of thelength of the tube. The end of the slit 75 connected with the secondbase portion-side expansion 74 b, on the other hand, is arranged fartherfrom the upstream-side notch 73 a than from the downstream-side notch 73b in the direction along the length of the tube.

As a result, effects similar to those of the second embodiment areproduced.

Further, in view of the fact that the two base portion-side expansions74 a, 74 b are tilted in opposite directions in the direction of airflow, the spring back when molding the base portion-side expansions 74a, 74 b can be reduced for an improved moldability.

Next, a fourth embodiment of the invention will be explained withreference to FIGS. 5A, 5B. In FIGS. 5A, 5B, component parts similar oridentical to those of the second embodiment are designated by the samereference numerals, respectively, and are not described again. FIG. 5Ais a plan view showing the insert 7 according to the fourth embodiment,and FIG. 5B is a front view of FIG. 5A.

As shown in FIGS. 5A, 5B, the base portion 71 of the insert 7 accordingto this embodiment is formed with two slits 75. According to thisembodiment, the two slits 75 are arranged with the length thereofsubstantially parallel to the length of the tubes. Of the two slits 75,the one arranged on the upstream side in the air flow is called a firstslit 75 a and the one arranged downstream side in the air flow a secondslit 75 b.

The base portion-side expansion 74 is split into three parts in thedirection along the air flow. The resultant three base portion-sideexpansions 74 a to 74 c are arranged substantially parallel to thedirection of air flow in such a manner as not to be superposed, one onanother, in the direction of air flow. Of the three base portion-sideexpansions 74, the one arranged upstream in the air flow is called afirst base portion-side expansion unit 74 a, the one arranged downstreamin the air flow a second base portion-side expansion 74 b, and the onearranged between the first base portion-side expansion 74 a and thesecond base portion-side expansion 74 c a third base portion-sideexpansion 74 c.

As shown in FIG. 5A, the three base portion-side expansions 74 a to 74 care coupled to each other through the two slits 75 a, 75 b. Morespecifically, one end of the first slit 75 a along the tube length isconnected to the first base portion-side expansion 74 a, and the otherend thereof to the third base portion-side expansion 74 c. Thedownstream end of the third base portion-side expansion 74 c along thedirection of air flow is connected to one end of the second slit 75 balong the tube length, and the other end thereof to the second baseportion-side expansion 74 b.

As a result, effects similar to those of the second embodiment areproduced.

Further, in view of the fact that the three base portion-side expansions74 a to 74 c are formed substantially in parallel to the direction ofair flow in such a manner as not to be superposed, one on another, inthe direction of air flow, the base portion-side expansion 74 is notrequired to be tilted from the direction of air flow, and therefore themoldability is improved.

Next, a fifth embodiment of the invention will be explained withreference to FIGS. 6A and 6B. In FIGS. 6A and 6B, the component partssimilar or identical to those of the first embodiment are designated bythe same reference numerals, respectively, and not described any more.FIG. 6A is a plan view showing the insert 7 according to the fifthembodiment, and FIG. 6B is a front view of FIG. 6A.

As shown in FIGS. 6A and 6B, the insert 7 according to this embodimentis formed with a notch 76. The notch 76 is formed by cutting the baseportion 71 diagonally from one end to the other end in the direction ofair flow in such a manner as to be tilted from the direction of airflow. As a result, the upstream and downstream ends of the notch 76 inthe air flow are prevented from being superposed, one on the other, inthe direction of air flow.

According to this embodiment, the notch 76 is formed continuously fromthe upstream end to the downstream end of the base portion 71 in the airflow. Also, the notch 76 is formed continuously in the ribs 72. Morespecifically, the portion of each rib 72 adjacent to the end of thenotch 76 is notched substantially in parallel to the direction along thetube stack. According to this embodiment, therefore, the insert 7 iscompletely separated by the notch 76.

As described above, by forming the notch 76 in the base portion 71 ofthe insert 7, the stress generated along the length of the insert 7 canbe absorbed.

Also, in view of the fact that the notch 76 is arranged diagonally withrespect to the direction of air flow, the stress absorber of the insert7, i.e. the portion of the insert 7 having little strength to hold thetube 2 can be dispersed along the tube length. In the case where theinternal pressure of the tube 2 increases, therefore, the tube 2 isprevented from being locally deformed by expansion, thereby making itpossible to prevent the tube 2 being broken.

Thus, the thermal distortion can be reduced while, at the same time, thepressure resistance performance is secured.

Further, in view of the fact that the stress generated along the lengthof the insert 7 can be absorbed simply by forming the notch 76 in theinsert 7, the pressure resistance performance can be secured with asimple configuration.

Next, a sixteenth embodiment of the invention will be explained withreference to FIGS. 7A and 7B. In FIGS. 7A and 7B, component partssimilar or identical to those of the fifth embodiment are designated bythe same reference numerals, respectively, and are not described again.FIG. 7A is a plan view showing the insert 7 according to the sixthembodiment, and FIG. 7B a front view of FIG. 7A.

As shown in FIGS. 7A and 7B, only one end (the upstream end in the airflow in this embodiment) of the notch 76 according to this embodiment isopen. More specifically, one end of the notch 76 in the direction of airflow is connected to an end of the base portion 71 in the direction ofair flow, and the other end (the downstream end in the air flow in thisembodiment) of the notch 76 is located within the base portion 71. Inother words, according to this embodiment, the insert 7 is notcompletely separated by the notch 76.

As described above, by opening only one end of this notch 76, one rib 72is left intact and, therefore, an undesired rigidity reduction can beavoided. As a result, the force to hold the tubes 2 can be increased,thereby reducing the thermal distortion while, at the same time,positively securing the pressure resistance performance.

Next, a seventh embodiment of the invention will be explained withreference to FIGS. 8A and 8B. In FIGS. 8A and 8B, component partssimilar or identical to those of the sixth embodiment are designated bythe same reference numerals, respectively, and are not described again.FIG. 8A is a plan view showing the insert 7 according to the seventhembodiment, and FIG. 8B a front view of FIG. 8A.

As shown in FIGS. 8A and 8B, the base portion 71 of the insert 7according to this embodiment is formed with three parallel notches 76.The three notches 76 are all formed by cutting the base portion 71, fromthe upstream end toward the downstream end thereof in the air flow.

By forming the three notches 76 in the base portion 71 in this way, thestress generated in the direction along the length of the insert 7 canbe positively absorbed. Thus, the thermal distortion can be reducedwhile, at the same time, the pressure resistance performance is secured.

Next, an eighth embodiment of the invention will be explained withreference to FIGS. 9A and 9B. In FIGS. 9A and 9B, component partssimilar or identical to those of the seventh embodiment are designatedby the same reference numerals, respectively, and are not describedagain. FIG. 9A is a plan view showing the insert 7 according to theeighth embodiment, and FIG. 9B is a front view of FIG. 9A.

As shown in FIGS. 9A and 9B, the base portion 71 of the insert 7 isformed with three parallel notches 76. According to this embodiment, thenotch 76 a arranged outside and along the tube length is formed bycutting the base portion 71, from the upstream end toward the downstreamend in the air flow. The notch 76 b arranged inside in the direction oftube stack, on the other hand, is formed by cutting the base portion 71from the downstream end to the upstream end in the air flow.

As a result, effects similar to those of the seventh embodimentdescribed above are achieved.

Next, a ninth embodiment of the invention will be explained withreference to FIGS. 10A and 10B. In FIGS. 10A and 10B, component partssimilar or identical to those of the seventh embodiment are designatedby the same reference numerals, respectively, and are not describedagain. FIG. 10A is a plan view showing the insert 7 according to theninth embodiment, and FIG. 10B a front view of FIG. 10A.

As shown in FIGS. 10A and 10B, the base portion 71 of the insert 7according to this embodiment is formed with four notches 76. Of the fournotches 76, two (hereinafter referred to as first notch portions 76 c)are formed by cutting the base portion 71, from the upstream end towardthe downstream end in the air flow. The two other notches (hereinafterreferred to as a second notch portion 76 d), other than the first notchportion 76 c, on the other hand, are formed by cutting the base portion71, from the downstream end toward the upstream end in the air flow.

The two notches of the first notch portion 76 c are arrangedsubstantially parallel to each other. The two notches of the secondnotch portion 76 d, on the other hand, are tilted in the oppositedirection to the first notch portion 76 c in the direction of air flow.Also, the two notches of the second notch portion 76 d are arrangedsubstantially in parallel to each other.

As a result, effects similar to those of the seventh embodimentdescribed above are produced.

Next, a tenth embodiment of the invention will be explained withreference to FIGS. 11A, 11B. In FIGS. 11A, 11B, component parts similaror identical to those of the fifth embodiment are designated by the samereference numerals, respectively, and are not described again. FIG. 11Ais a plan view showing the insert 7 according to the tenth embodiment,and FIG. 11B a front view of FIG. 11A. FIG. 12 is a perspective viewshowing the insert 7 according to the tenth embodiment.

As shown in FIGS. 11A, 11B and 12, the ends of the notch 76 (hereinafterreferred to as the rectangular portions 760) in the direction of airflow according to this embodiment are substantially rectangular andlarger than the other parts of the notch 76. Also, the portion of eachrib 72 adjacent to the corresponding rectangular portion 760 is formedwith a rib-side expansion 77 of the rib 72 having a substantiallyU-shaped cross section. According to this embodiment, the rib-sideexpansions 77 are formed inward of the insert 7 in the direction of airflow.

As described above, by forming the notch 76 in the base portion 71 andthe rib-side expansions 77 of the pair of the ribs 72, the stressgenerated in the direction along the length of the insert can bepositively absorbed.

Also, the diagonal arrangement of the notch 76, with respect to thedirection of air flow, makes it possible to disperse the stress absorberof the insert 7, i.e. the portion of the insert 7 having a weak force tohold the tubes 2, over the length of the tube. As a result, in the casewhere the internal pressure of the tube 2 increases, the tube 2 isprevented from being locally expanded and deformed, thereby making itpossible to prevent the tube 2 from being broken.

As a result, thermal distortion is positively reduced while at the sametime the pressure resistance performance is secured.

Next, the eleventh embodiment of the invention is explained withreference to FIGS. 13 and 14. The component parts similar to those ofthe first embodiment described above are designated by the samereference numerals, respectively, and not explained again.

FIG. 13 is a perspective view showing the insert 7 according to theeleventh embodiment, FIG. 14A is a view taken along arrow A in FIG. 13,FIG. 14B is a sectional view taken in line B-B in FIG. 13, and FIG. 14Cis a sectional view taken in line C-C in FIG. 13.

As shown in FIGS. 13 and 14A to 14C, the base portion 71 of the insert 7is formed with base portion-side ribs (protrusions) 78 projected outwardalong the direction in which the tubes 2 are stacked and extendingsubstantially parallel to the length of the insert 7. The baseportion-side ribs 78 have an end thereof connected to the baseportion-side expansion 74. According to this embodiment, the other endof each of the base portion-side ribs 78 is arranged at the longitudinalends of the base portion 71.

The base portion-side ribs 78 are each arranged on each side of the baseportion-side expansion 74, or specifically, one each on each of thesides of the base portion-side expansion 74 on the base portion 71. Thetwo base portion-side ribs 78 are arranged on one and the other sides,respectively, of the center line L across the length of the insert 7(hereinafter referred to simply as the center line) of the base portion71 in the direction of air flow. According to this embodiment, the twobase portion-side ribs 78 are connected to one and the other ends,respectively, of the base portion-side expansion 74 in the direction ofair flow.

Also, as shown in FIGS. 14B and 14C, the base portion-side ribs 78 areformed to have a substantially semicircular section.

Upon application of pressure thereto (when the internal pressure of thetubes 2 rises), the whole radiator 1 is deformed to expand along thedirection in which the tubes 2 are stacked, and upon vehicle vibration,the whole radiator 1 is deformed both along the length of the tubes 2and along the direction in which the tubes 2 are stacked. By forming thebase portion-side expansion 74 with the section thereof expandedsubstantially in the shape of U on the base portion 71 of the insert 7,on the other hand, the stress generated along the length of the insert 7can be absorbed. Further, according to this embodiment, the baseportion-side ribs 78 projected outward along the direction in which thetubes 2 are stacked are formed on the base portion 71 of the insert 7,so that the stiffness of the insert 7 along the direction in which thetubes 2 are stacked can be improved. As a result, the resistance to boththe pressure and the earthquake is improved.

The stress, if generated along the length of the insert 7, isconcentrated at the connector between the base portion 71 of the insert7 and the base portion-side expansion 74 and may break the connector. Byconnecting one end of each of the base portion-side ribs 78 to the baseportion-side expansion 74, on the other hand, the stress concentrationat the connector between the base portion 71 and the base portion-sideexpansion 74 is prevented.

Also, the stiffness of the insert 7 along the direction in which thetubes 2 are stacked can be secured by the base portion-side ribs 78, andtherefore, the height of the side ribs 72 (the length along thedirection in which the tubes 2 are stacked) can be reduced. Therefore,even in the case where the mounting space of the radiator 1 is limited,the core portion 4 can be enlarged by the amount corresponding to theheight reduction of the side ribs 72, thereby making it possible toimprove the heat exchange performance.

Also, one each of the base portion-side ribs 78 is arranged on each sideof the base portion-side expansion 74, and therefore, the baseportion-side ribs 78 can be arranged over a wide range in thelongitudinal direction of the insert 7, thereby making it possible tofurther increase the stiffness of the insert 7 along the direction inwhich the tubes 2 are stacked. Thus, the pressure resistance and thequake resistance are improved.

Further, the base portion-side ribs 78 are arranged on one and the othersides of the center line L of the base portion 71, and therefore, thebase portion-side ribs 78 can be arranged over a wide range on theinsert 7 in the direction of air flow. Thus, the stiffness of the insert7 along the direction in which the tubes 2 are stacked can be furtherincreased. Thus, the pressure resistance and the quake resistance can beimproved.

Next, the twelfth embodiment of the invention is explained withreference to FIGS. 15 and 16. The twelfth embodiment, compared with theeleventh embodiment described above, is different in that the side ribs72 are omitted. The component parts similar to those of the eleventhembodiment are designated by the same reference numerals, respectively,and not explained.

FIG. 15 is a perspective view showing the insert 7 according to thetwelfth embodiment. FIG. 16A is a view taken along arrow in FIG. 15,FIG. 16B is a sectional view taken in line E-E in FIG. 15, and FIG. 16Cis a sectional view taken in line F-F in FIG. 15. As shown in FIGS. 15and 16A to 16C, the insert 7 has only the base portion 71.

As described above, by providing the base portion 71 of the insert 7with the base portion-side ribs 78 projected outward along the directionin which the tubes 2 are stacked, the stiffness of the insert 7 alongthe direction in which the tubes 2 are stacked can be increased, andtherefore, the side ribs can be omitted. As a result, even in the casewhere the mounting space of the radiator 1 is limited, the core portion4 can be increased in size by the amount corresponding to the side ribsremoved. Thus, heat exchange performance is improved.

Next, the thirteenth embodiment of the invention is explained withreference to FIG. 17. The thirteenth embodiment is different from thetwelfth embodiment in that the base portion-side ribs 78 are differentlyarranged. The component parts similar to those of the twelfth embodimentare designated by the same reference numerals, respectively, and notexplained again.

FIG. 17 is a perspective view showing the insert 7 according to thethirteenth embodiment. As shown in FIG. 17, the two base portion-sideribs 78 arranged on the two sides, respectively, of the baseportion-side expansion 74 of the base portion 71 are connected to thebase portion-side expansion 74 in the neighborhood of the center of airflow. As a result, the effects similar to those of the twelfthembodiment are obtained.

Next, the fourteenth embodiment of the invention is explained withreference to FIG. 18. The fourteenth embodiment is different from theeleventh embodiment in that the base portion-side ribs 78 aredifferently arranged. The component parts similar to those of theeleventh embodiment are designated by the same reference numerals,respectively, and not explained more.

FIG. 18 is a perspective view showing the insert 7 according to thefourteenth embodiment. As shown in FIG. 18, the two base portion-sideribs 78 arranged on both sides of the base portion-side expansion 74 ofthe base portion 71 are arranged on the center line L of the baseportion 71. Also, the two base portion-side ribs 78 are connected to thecentral part of the base portion-side expansion 74 in the direction ofair flow. As a result, similar effects to those of the eleventhembodiment are obtained.

Next, the fifteenth embodiment of the invention is explained withreference to FIG. 19. The fifteenth embodiment is different from thetwelfth embodiment in the provision of second base portion-side ribs 78a. The component parts similar to those of the twelfth embodiment aredesignated by the same reference numerals, respectively, and notdescribed any more.

FIG. 19 is a perspective view showing the insert 7 according to thefifteenth embodiment. As shown in FIG. 19, the part of the base portion71 not having the base portion-side ribs 78 is formed with the secondbase portion-side ribs 78 a projected outward along the direction inwhich the tubes 2 are stacked and extending in the directionsubstantially parallel to the length of the insert 7. According to thisembodiment, the second base portion-side ribs 78 a have a substantiallysemicircular section.

Also, each of the second base portion-side ribs 78 a is arranged on oneof the two sides of the base portion-side expansion 74. The two secondbase portion-side ribs 78 a are arranged on one and the other sides,respectively, of the center line L of the base portion 71. Also, on oneand the other sides of the center line L of the base portion 71, thesecond base portion-side ribs 78 a are arranged in opposed relation withthe base portion-side ribs 78, respectively, with respect to the baseportion-side expansion 74.

As explained above, the part of the base portion 71 not having the baseportion-side ribs 78 is formed with the second base portion-side ribs 78a, thereby making it possible to further increase the stiffness of theinsert 7 along the direction in which the tubes 2 are stacked. As aresult, the pressure resistance and the quake resistance are furtherimproved.

Also, by arranging each of the second base portion-side ribs 78 on eachof the two sides of the base portion-side expansion 74, the second baseportion-side ribs 78 a can be arranged over a wide range along thelength of the insert 7. Further, the two second base portion-side ribs78 a are arranged on one and the other sides of the center line L of thebase portion 71, so that the second base portion-side ribs 78 can bearranged over a wide range of the insert 7 in the direction of air flow.Further, on one and the other sides of the center line L, the secondbase portion-side ribs 78 a are arranged in opposed relation with thebase portion-side ribs 78, respectively, with respect to the baseportion-side expansion 74, and therefore, the base portion-side ribs 78or the second base portion-side ribs 78 a can be arranged substantiallyover the entire area of the base portion 71. As a result, the stiffnessof the insert 7 along the direction in which the tubes 2 are stacked canbe further increased, thereby improving the pressure resistance and thequake resistance further.

Next, the sixteenth embodiment of the invention is explained withreference to FIG. 20. The sixteenth embodiment is different from thefifteenth embodiment in that an end of each of the second baseportion-side ribs 78 a is connected to the base portion-side expansion74. The component parts similar to those of the fifteenth embodiment aredesignated by the same reference numerals, respectively, and notexplained any more.

FIG. 20 is a perspective view showing the insert 7 according to thesixteenth embodiment. As shown in FIG. 20, the second base portion-sideribs 78 a each have an end thereof connected to the base portion-sideexpansion 74. According to this embodiment, the base portion-side ribs78 and the second base portion-side ribs 78 a are aligned with eachother on each of one and the other sides of the center line L. Also, thetwo second base portion-side ribs 78 a are connected one and the otherends, respectively, of the base portion-side expansion 74 in thedirection of air flow.

As explained above, an end of each of the second base portion-side ribs78 a is connected to the base portion-side expansion 74, and therefore,the stress concentration at the connector between the base portion 71and the base portion-side expansion 74 is positively prevented.

Next, the seventeenth embodiment of the invention is explained withreference to FIG. 21. The component parts similar to those of thesixteenth embodiment are designated by the same reference numerals,respectively, and not explained again.

FIG. 21 is a perspective view showing the insert 7 according to theseventeenth embodiment of the invention. As shown in FIG. 21, the baseportion-side ribs 78 and the second base portion-side ribs 78 a areconnected to other than the ends of the base portion-side expansion 74in the direction of air flow.

More specifically, the base portion-side ribs 78 and the second baseportion-side ribs 78 a arranged upstream of the center line L of thebase portion 71 in the air flow are connected to the part of the baseportion-side expansion 74 upstream of the center line L in the air flow.Also, the base portion-side ribs 78 and the second base portion-sideribs 78 a arranged downstream of the center line L of the base portion71 in the air flow are connected to the part of the base portion-sideexpansion 74 downstream of the center line L in the air flow. As aresult, the effects similar to those of the sixteenth embodiment areachieved.

Next, the eighteenth embodiment of the invention is explained withreference to FIG. 22. The eighteenth embodiment is different from thefourteenth embodiment in the provision of the second base portion-sideribs 78 a. The component parts similar to those of the fourteenthembodiment are designated by the same reference numerals, respectively,and not explained again.

FIG. 22 is a plan view showing the insert 7 according to the eighteenthembodiment of the invention. As shown in FIG. 22, the part of the baseportion 71 lacking the base portion-side ribs 78 is formed with thesecond portion-side ribs 78 a projected outward along the direction inwhich the tubes 2 are stacked and extending in the directionsubstantially parallel to the length of the insert 7. The second baseportion-side ribs 78 a are each arranged on one of the two sides of thebase portion-side expansion 74. The two base portion-side ribs 78 a arearranged on one and the other sides, respectively, of the center line Lof the base portion 71.

According to this embodiment, the two base portion-side ribs 78 a areeach connected to the other end (the side not connected with the baseportion-side expansion 74) of the two base portion-side ribs 78,respectively. More specifically, the second base portion-side ribs 78 aarranged upstream of the center line L of the base portion 71 in the airflow are connected to the surface of the base portion-side ribs 78upstream in the air flow. Also, the second base portion-side ribs 78 aarranged downstream of the center line L of the base portion 71 in theair flow are connected to the surface of the base portion-side ribs 78 adownstream in the air flow.

As explained above, the part of the base portion 71 not having the baseportion-side ribs 78 has the second base portion-side ribs 78 a,respectively, and therefore, the stiffness of the insert 7 along thedirection in which the tubes 2 are stacked is further improved. As aresult, the pressure resistance and the quake resistance are improved.

Next, the nineteenth embodiment of the invention is explained withreference to FIGS. 23, 24. The component parts similar to those of the5th embodiment are designated by the same reference numerals,respectively, and not explained again.

FIG. 23 is a perspective view showing the insert 7 according to thenineteenth embodiment of the invention. As shown in FIG. 23, a firstnotch 76 is formed from one end to the other of the base portion 71 ofthe insert 7 at an angle to the direction of air flow. The first notch76 is also formed continuously to the side ribs 72. Specifically, thetilt angle θ₁ of the part of the first notch 76 formed on the baseportion 71 to the air flow is equal to the tilt angle θ₂ of the part ofthe first notch 76 formed on the side ribs 72 to the direction in whichthe tubes 2 are stacked. Also, the ends of the first notch 76 arearranged in the plane of a pair of the side ribs 72, respectively, andtherefore, the side ribs 72 are not completely divided.

The pair of the side ribs 72 are formed with a second notch 79 inwardfrom the outer end thereof along the direction in which the tubes 2 arestacked. The second notches 79 each have one end thereof open, andaccording to this embodiment, the other end (the end not open) of eachof the second notches 79 is arranged in the plane of the side ribs 72.Also, the second notches 79 are each formed substantially in parallel tothe first notch 76.

According to this embodiment, the second notch 79 formed on the side rib72 downstream in the air flow (hereinafter referred to as thedownstream-side second notch 79 b) along the length of the insert 7, asviewed from the first notch 76, is formed on the same side as the secondnotch 79 on the side rib 72 upstream in the air flow (hereinafterreferred to as the upstream-side second notch 79 a). Specifically, thedownstream-side second notch 79 b is arranged on the same side as theupstream-side second notch 79 a with respect to the first notch 76 inthe direction along the length of the insert 7.

FIG. 24 is a plan view schematically showing the insert 7 before bendingthe side ribs 72 according to the nineteenth embodiment. As shown inFIG. 24, according to this embodiment, the first and second notches 76,79 are formed at the same time that the insert 7 is press formed. Theends of the insert 7 with the first and second notches 76, 79 formedthereon along the short side thereof are bent in the same directionthereby to form the side ribs 72, thereby completing the insert 7 shownin FIG. 23.

As explained above, the first notch 76 is extended to the side ribs 72,and the ends of the first notch 76 are arranged in the plane of the pairof the side ribs 72, respectively. Thus, the side ribs 72 are notcompletely divided, and therefore, the unnecessary decrease of thestiffness of the insert 7 can be avoided. As a result, the pressureresistance and the quake resistance can be positively secured.

In view of the fact that the ends of the first notch 76 are arranged inthe plane of the side rib pair 72, respectively, the stress generatedalong the length of the insert 7 is difficult to absorb. Therefore, thesecond notches 79 substantially in parallel to the first notch 76 areformed from the outer end of the side ribs 72 along the direction inwhich the tubes 2 are stacked. In this way, the stress along the lengthof the insert 7 can be easily absorbed. As a result, the thermaldistortion can be further reduced.

Further, the first and second notches 76, 79 may be formed before pressforming the insert 7. Thus, the process of forming the notches bycutting the insert 7 is not required after forming the core 4 by brazingthe insert 7 together with the tubes 2 and the fins 3. As a result, theformability is improved.

Next, the twentieth embodiment of the invention is explained withreference to FIG. 25. The twentieth embodiment is different from thenineteenth embodiment in that the other end of each of the secondnotches 79 of the insert 7 is arranged at a different position. Thecomponent parts similar to those of the nineteenth embodiment aredesignated by the same reference numerals, respectively, and notexplained more.

FIG. 25 is a perspective view showing the insert 7 according to thetwentieth embodiment. As shown in FIG. 25, the other end (the end notopen) of each second notch 79 is arranged in the plane of the baseportion 71 of the insert 7. As a result, the effects similar to those ofthe nineteenth embodiment are achieved.

Next, the twenty-first embodiment of the invention is explained withreference to FIG. 26. The twenty-first embodiment is different from thetwentieth embodiment in that the second notches 79 are arranged atdifferent positions. The component parts similar to those of thetwentieth embodiment are designated by the same reference numerals,respectively, and not explained more.

FIG. 26 is a perspective view showing the insert 7 according to thetwenty-first embodiment. As shown in FIG. 26, the downstream-side secondnotch 79 b is arranged on the side of the first notch 76 far from theupstream-side second notch 79 a along the length of the insert 7.Specifically, the downstream-side second notch 79 b is arranged on theother side of the first notch 76 far from the upstream-side notch 79 ain the longitudinal direction of the insert 7. As a result, the effectssimilar to those of the twentieth embodiment are achieved.

Next, the twenty-second embodiment of the invention is explained withreference to FIG. 27. The twenty-second embodiment is different from thetwenty-first embodiment in the provision of third notches 80. Thecomponent parts similar to those of the twenty-first embodiment aredesignated by the same reference numerals, respectively, and notexplained more.

FIG. 27 is a perspective view showing the insert 7 according to thetwenty-second embodiment. As shown in FIG. 27, a pair of side ribs 72are each formed with the third notch 80 inward from the outer end alongthe direction in which the tubes 2 are stacked. The third notches 80each have only one end thereof open, and according to this embodiment,the other end (the end not opened) of each of the third notches 80 isarranged in the plane of the side ribs 72. Also, the third notches 80are formed substantially in parallel to the first and second notches 76,79.

According to this embodiment, the third notch 80 formed on the side rib72 upstream in the air flow (hereinafter referred to as theupstream-side third notch 80 a) is arranged on the side of theupstream-side second notch 79 a far from the first notch 76. Also, thethird notch 80 formed on the side rib 72 downstream in the air flow(hereinafter referred to as the downstream-side third notch 80 b) isarranged on the side of the first notch 76 far from the downstream-sidesecond notch 79 b. The third notches 80 are also formed at the same timethat the insert 7 is press formed.

As explained above, the insert 7 is formed with the second and thirdnotches 79, 80 substantially in parallel to the first notch 76 from theouter end of the side ribs 72 along the direction in which the tubes 2are stacked. Thus, the stress generated along the length of the insert 7can be absorbed more easily. As a result, the thermal distortion can befurther reduced.

Finally, other embodiments will be described. Although the embodimentsdescribed above are an application of the invention to the cross-flowradiator in which the cooling water flows in horizontal direction.Nevertheless, this invention is applicable also to the down-flowradiator in which the cooling water flows vertically.

Also, this invention is not limited to the embodiments described abovein which the stress absorber, of the insert 7, is not in contact withthe core portion 4. As an alternative, the stress absorber of the insert7 may be in contact with the core portion 4.

Further, unlike in the seventh and eighth embodiments described above inwhich three notches 76 are formed in the base portion 71, two or four ormore notches 76 may be formed.

In similar fashion, in spite of the fact that the base portion 71 isformed with four notches 76 according to the ninth embodiment, two orthree or not less than five notches may be formed with equal effect.

The base portion-side ribs 78, though formed with a substantiallysemicircular section according to the eleventh to eighteenthembodiments, may alternatively have the section of other shapes such astriangle or rectangle.

In similar fashion, according to the fifteenth to eighteenth embodimentsdescribed above, the second base portion-side ribs 78 a are formed tohave a substantially semicircular section. Nevertheless, the section maybe in any of other shapes including a triangle and a rectangle.

While the invention has been described by reference to specificembodiments chosen for purposes of illustration, it should be apparentthat numerous modifications could be made thereto, by those skilled inthe art, without departing from the basic concept and scope of theinvention.

1. A heat exchanger comprising: a core portion including a plurality of tubes with a heat medium flowing therein; a pair of header tanks extending in a direction perpendicular to the length of the tubes at the longitudinal ends of the tubes and communicating with the tubes; and a pair of inserts arranged substantially parallel to the length of the tubes, and in such a manner as to contact the core portion at the ends of the core portion to transfer the heat from the core portion, and having the ends thereof supported on the header tanks; wherein a stress absorber to absorb the stress generated along the length of each insert is formed in the insert; the stress absorber is formed over each insert from the upstream side to the downstream side in the air flow; the stress absorber is arranged in such a manner that the most upstream end and the most downstream end thereof in the air flow are not superposed, one on the other, along the direction of air flow; each insert includes a base portion having a surface substantially parallel to the flat surfaces of the tubes and extending substantially parallel to the length of the tubes, and a pair of ribs are projected in a direction substantially perpendicular to the base portion from the ends of the base portion in the direction of air flow and are extended substantially parallel to the length of the tubes; the portions of the ribs corresponding to the most upstream end and the most downstream end of the stress absorber are formed with notches, respectively; and each stress absorber constitutes a base portion-side expansion of the base portion having a substantially U-shaped cross section.
 2. A heat exchanger according to claim 1, wherein the base portion-side expansion is formed diagonally with respect to the direction of air flow.
 3. A heat exchanger according to claim 1, wherein the base portion-side expansion is split into a plurality of parts in the direction of air flow, and the plurality of the base portion-side expansions are coupled to each other through slits formed in the base portion.
 4. A heat exchanger according to claim 3, wherein the plurality of the base portion-side expansions are not arranged in alignment.
 5. A heat exchanger according to claim 3, wherein the plurality of the base portion-side expansions are tilted in different directions with respect to the direction of air flow.
 6. A heat exchanger according to claim 3, wherein the plurality of the base portion-side expansions are arranged substantially parallel to the direction of air flow in such a manner as not to be superposed, one on another, in the direction of air flow.
 7. A heat exchanger comprising: a core portion including a plurality of tubes with a heat medium flowing therein; a pair of header tanks extending in a direction perpendicular to the length of the tubes at the longitudinal ends of the tubes and communicating with the tubes; and a pair of inserts arranged substantially parallel to the length of the tubes, and in such a manner as to contact the core portion at the ends of the core portion to transfer the heat from the core portion, and having the ends thereof supported on the header tanks; wherein a stress absorber to absorb the stress generated along the length of each insert is formed in the insert; the stress absorber is formed over each insert from the upstream side to the downstream side in the air flow; the stress absorber is arranged in such a manner that the most upstream end and the most downstream end thereof in the air flow are not superposed, one on the other, along the direction of air flow; the tubes each have a flat cross section in the direction of air flow, and each insert includes a base portion having a surface substantially parallel to the flat surface of the tubes and extending in the direction substantially parallel to the length of the tubes and a pair of ribs projected in the direction substantially perpendicular to the base portion and extending in the direction substantially parallel to the length of the tubes, and the stress absorber is a notch cut in the base portion diagonally to the direction of air flow.
 8. A heat exchanger according to claim 7, wherein only one end of the notch is open.
 9. A heat exchanger according to claim 7, comprising a plurality of notches.
 10. A heat exchanger according to claim 9, wherein the plurality of the notches are tilted in different directions with respect to the direction of air flow.
 11. A heat exchanger according to claim 7, comprising a plurality of notches each having only one open end; the open ends of the plurality of the notches are arranged on the base portion and alternate between the upstream side and the downstream side in the air flow.
 12. A heat exchanger according to claim 7, wherein the notch extends to the side ribs, the ends of the notch are arranged in the plane of the pair of the side ribs, respectively, the insert is formed with second notches substantially in parallel to the notch from the outer end of the side ribs along the direction in which the tubes are stacked, and the second notches each have only one end thereof open.
 13. A heat exchanger according to claim 7, wherein the notch is formed in the base portion, the portion of each of the pair of the ribs adjoining the corresponding notch is formed with a U-shaped rib-side expansion in the direction of air flow, and each stress absorber includes the corresponding rib-side expansion.
 14. A heat exchanger comprising: a core portion including a plurality of tubes with a heat medium flowing therein; a pair of header tanks extending in a direction perpendicular to the length of the tubes at the longitudinal ends of the tubes and communicating with the tubes; and a pair of inserts arranged substantially parallel to the length of the tubes, and in such a manner as to contact the core portion at the ends of the core portion to transfer the heat from the core portion, and having the ends thereof supported on the header tanks; wherein a stress absorber to absorb the stress generated along the length of each insert is formed in the insert; the stress absorber is formed over each insert from the upstream side to the downstream side in the air flow; the stress absorber is arranged in such a manner that the most upstream end and the most downstream end thereof in the air flow are not superposed, one on the other, along the direction of air flow; the insert is formed with protrusions projected outward thereof along the direction in which the tubes are stacked, and the protrusions are connected to a stress absorber.
 15. A heat exchanger comprising: a core portion including a plurality of tubes with a heat medium flowing therein; a pair of header tanks extending in a direction perpendicular to the length of the tubes at the longitudinal ends of the tubes and communicating with the tubes; and a pair of inserts arranged substantially parallel to the length of the tubes, and in such a manner as to contact the core portion at the ends of the core portion to transfer the heat from the core portion, and having the ends thereof supported on the header tanks; wherein a stress absorber to absorb the stress generated along the length of each insert is formed in the insert; the stress absorber is formed over each insert from the upstream side to the downstream side in the air flow; the stress absorber is arranged in such a manner that the most upstream end and the most downstream end thereof in the air flow are not superposed, one on the other, along the direction of air flow; the tubes have a flat section along the direction of air flow, the insert includes a base portion having a surface substantially parallel to the flat surface of the tubes and extending in the direction substantially parallel to the length of the tubes, the base portion has base portion-side ribs projected outward along the direction in which the tubes are stacked and extending in the direction substantially parallel to the length of the insert, the stress absorber is a base portion-side expansion having the section expanded substantially in the shape of U, and an end of each of the base portion-side ribs is connected to the base portion-side expansion.
 16. A heat exchanger according to claim 15, wherein the insert has a pair of side ribs projected in the direction substantially perpendicular to the base portion from the ends of the base portion along the direction of air flow, and the portions of the side ribs corresponding to the most upstream end and the most downstream end of the base portion-side expansion are formed with notches, respectively.
 17. A heat exchanger according to claim 15, wherein the base portion-side ribs are formed on both sides, respectively, of the base portion-side expansion.
 18. A heat exchanger according to claim 17, wherein the base portion-side ribs are arranged on one and the other sides, respectively, of the center line (L) of the base portion across the length of the insert in the air flow.
 19. A heat exchanger according to claim 18, wherein the base portion is formed with second base portion-side ribs projected outward along the direction in which the tubes are stacked and extending in the direction substantially parallel to the length of the insert, the base portion-side ribs are formed on both sides, respectively, of the base portion-side expansion and arranged on one and the other sides, respectively, of the center line (L) of the base portion across the length of the insert in the air flow, and the second base portion-side ribs are arranged in opposed relation to the base portion-side ribs, respectively, with respect to the base portion-side expansion on each of one and the other sides of the center line (L).
 20. A heat exchanger according to claim 19, wherein the second base portion-side each have an end thereof connected to the base portion-side expansion.
 21. A heat exchanger according to claim 15, wherein the base portion-side ribs are formed on both sides, respectively, of the base portion-side expansion and also on the center line (L) of the base portion across the length of the insert in the air flow.
 22. A heat exchanger according to claim 15, wherein the base portion is formed with second base portion-side ribs projected outward along the direction in which the tubes are stacked and extending in the direction substantially parallel to the length of the insert.
 23. A heat exchanger according to claim 15, wherein the base portion-side ribs are aligned on both sides, respectively, of the base portion-side expansion, the base portion is formed with second base portion-side ribs projected outward along the direction in which the tubes are stacked and extending in the direction substantially parallel to the length of the insert, and the second base portion-side ribs are arranged on one and the other sides, respectively, of the base portion-side expansion and connected to the base portion-side ribs. 